The original 'classic Tannoys' had crossover components that weren't designed or capable of good high power & high SPL.
This could go a long way as to explain your experience with them.
Small saturated inductors don't lend themselves to good sound.
Ditto Altec VoTT till right at the end when they 'borrowed'/tweak'? the HIFI oriented Model 19's XO, horn combo.
Isn't this a quite extreme scenario? Most loudspeakers have only one driver per "way", but most often "ways" are connected parallel to the source (amp) Fully serial xo are rare.
The topic was drivers in series vs. parallel.
I was describing it when using a parallel xo, not a series one.
I was describing it when using a parallel xo, not a series one.
The series/parallel roles would be reversed if we were using a transconductance amplifier, and mixed for a low damping factor voltage amp.
Speak for yourself there Mister. These are my cozy den speakers.
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What?
I can't hear you!
Dave, I know you already know the answer. These are not used at the level where stereo imaging is part of the conversation. They are the grandest of the 'single pairs' I assembled and they began to sound good in the great outdoors of Vancouver Island after Jesse stepped in to help by twisting the knobs the right direction.
It was like the third festival where you guys yelled at me from the balcony. I was so glad I couldn't hear what you were saying. 😎
I can't hear you!
Dave, I know you already know the answer. These are not used at the level where stereo imaging is part of the conversation. They are the grandest of the 'single pairs' I assembled and they began to sound good in the great outdoors of Vancouver Island after Jesse stepped in to help by twisting the knobs the right direction.
It was like the third festival where you guys yelled at me from the balcony. I was so glad I couldn't hear what you were saying. 😎
There is one small downside with series'd woofers, there is no damping for out-of-phase movement because the produced back-EMF cancels itself and is not available for damping. There can be some hint of one-note-bass because for any out of-phase excitation (for whatever reasons, like any non-identical behavior in general) the combo will ring undamped.
In series connection the back EMFs don't cancel, they superimpose on each other, which could cause interesting interactions with driver difference.
http://www.cartchunk.org/audiotopics/SeriesSpeaker.pdf
Damping remains similar:
That said, going back to the OP's dual 4 ohm driver example, the series nominal 8 ohm load will have about four times the damping available as a parallel 2 ohm load using the same gauge wire.
https://www.bennettprescott.com/downloads/dampingfactor.pdf
Back in the 1980's Harry Witz of dB Sound conducted A/B experiments with their flown EV MTL cabinets (four 8 ohm 18" drivers per cabinet), and with the length of cable they used, (as much as 175' was required for hangs in some of the tall arenas) the increased "punch" given by increasing the damping factor going from a 2 ohm load to a pair of 8 ohm loads bridged mono on the same wire made it appear that the woofers had gained between 3 to 6 dB more "level", even though by power or SPL readings they would be virtually the same.
Art
http://www.cartchunk.org/audiotopics/SeriesSpeaker.pdf
Damping remains similar:
That said, going back to the OP's dual 4 ohm driver example, the series nominal 8 ohm load will have about four times the damping available as a parallel 2 ohm load using the same gauge wire.
https://www.bennettprescott.com/downloads/dampingfactor.pdf
The exact opposite happens in practice when damping is compromised by long cable lengths.
Back in the 1980's Harry Witz of dB Sound conducted A/B experiments with their flown EV MTL cabinets (four 8 ohm 18" drivers per cabinet), and with the length of cable they used, (as much as 175' was required for hangs in some of the tall arenas) the increased "punch" given by increasing the damping factor going from a 2 ohm load to a pair of 8 ohm loads bridged mono on the same wire made it appear that the woofers had gained between 3 to 6 dB more "level", even though by power or SPL readings they would be virtually the same.
Art
This is from another thread, but the reason I show it is because when you have this many drivers in series, if one goes faulty [but not open circuit]
like a 'scratchy voice coil/loose windings', the fault can reflect through the entire 'chain' making trouble shooting quite a difficult quagmire !!!
Of course it cancels for same out of-phase movements, one driver produces a certain microphonic voltage and the other driver produces the same voltage but opposite polarity, total thus (close to) zero. There is nothing a short circuit on driving side can damp.
When you have series'd woofers terminated with a short, and you manually tap or push the front woofer inward and release it, the other woofer follows with the opposite movement and then they both ring while going back to their rest position. The short (==the amp) as zero control over that, it can only control the common-mode part of the movement, and of course you don't see it in the usual T/S parameter measurements. And that out-of-phase movement is audible even though most of it cancels acoustically. When the woofers are mounted back-to-back force-canceling with a large distance the canceling is reduced, you basically now have a dipole speaker.
One would think this out-of-phase movement will never be triggered as the driving signal and the air load etc is always in phase but in practice there are enough differences to trigger it, notably when going near or beyond the linearity limits. The result is that, for example a loud kick drum has a certain ringing decay to it (the one-note bass) which goes away when each driver has its own amp or when they are wired in parallel. This is what we found experimentally (with a large active tower subwoofer) and it fully conforms to theory.
No, bipole for the signal. Non-linearities might be opposite phase more or less, but I believe that effect would be simply theoretical, not even measurable at some realistic distance. And regardless of mountin on same vs. opposite side (regarding woofers that are lowpassed in a 3-way speaker or a subwoofer)
If one pushes in other woofer connected parallel in a closed box, the other moves outward as well.
This scenario of pushing one of two (identical) drivers wired in parallel and which way the other moves (in or out)
is dependent on enclosure size & type. In a small sealed enclosure with high 'Air Spring', the other driver can move
in OR out or even remain essentially stationary > this all depends on the Q parameters of the drivers VS the air spring.
In a VERY LARGE enclosure, two drivers wired in parallel WILL exhibit > push one in and the other follows in.
As you can see, there is not actually a 'one golden rule' that actually applies. This is all evident with drivers disconnected from amp. damping.
There are actual errors in the last two posts 😎
PS.
Modern recording of Kick Drums do not exhibit a long 'resonant/ring tail'.
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I have two different serially connected woofers. Details of drivers and amps for those interested in maths are in links.
The subwoofer has separate 235 liter boxes and 15" Dayton DCS380-4 woofers. Having the Hypex DS2.0 amp on or off doesn't matter, visually the other cone doesn't move at all when one is pushed in fast or slowly.
3-way speaker has two ScanSpeak 21W woofers sharing roughly 60 liter sealed box, powered by Hypex Ncore FA123. Wires connected or not, power on or off, the other moves out when one is pushed in.
As well, two serial 8ohm 8" woofers in open air, one being pushed the other didn't move visually.
I said this earlier, the benefit of doubling in any way has more benefits than problems. Just be careful to not get too low inductance in the system (with xo)
The subwoofer has separate 235 liter boxes and 15" Dayton DCS380-4 woofers. Having the Hypex DS2.0 amp on or off doesn't matter, visually the other cone doesn't move at all when one is pushed in fast or slowly.
3-way speaker has two ScanSpeak 21W woofers sharing roughly 60 liter sealed box, powered by Hypex Ncore FA123. Wires connected or not, power on or off, the other moves out when one is pushed in.
As well, two serial 8ohm 8" woofers in open air, one being pushed the other didn't move visually.
I said this earlier, the benefit of doubling in any way has more benefits than problems. Just be careful to not get too low inductance in the system (with xo)
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